I think you should take your question even farther: before humans knew that one’s brain is where one’s thoughts come from, did we even have a word or concept for “thought”? I doubt it.
@CyanoticWasp Are you sure that’s an ancient statue? Maybe I’m wrong, but I think your time-line is off. I have never seen that statue before, but from its appearance I would say it looks like Jesus and not even a classical Jesus. I’m pretty sure whoever made that statue knew about brains.
Edit: After looking around, I found your statue. It appears on the site of St. Joseph’s Old Cathedral in Oklahoma City. This is what’s written about it on their website: ” ‘And Jesus Wept’ statue: Behind St. Joseph Old Cathedral stands a shrine in remembrance of the April 19, 1995, bombing of the Alfred P. Murrah Federal Building in Oklahoma City. The focal point of the shrine is a statue of Jesus who faces away from the tragic sight; He holds His face in His hands in sorrow.” I haven’t found any evidence to suggest it’s a copy of an old design – do you have reason to suggest that it is?